I haven't had any luck finding 1/3 N batteries for my Nikon FM2. Sometimes the manufacturers call it CR1/3N; Duracell calls it the DL1/3N.
The major distributor of batteries, Filmaxel, doesn't have any. I can't mail order it from Amazon because of regulations regarding the shipping of lithium batteries. They can only be brought in through carry-on baggage as "spare batteries for your devices."
I can use 2 SR44 (which are available) but prefer the 1/3N.
TIA
GB